An accelerator is essentially equipped with: an accelerating structure which internally accelerates particles such as electrons, positrons, and protons; a klystron which supplies radio frequency for accelerating the particles to the accelerating structure; a waveguide which connects together the klystron and the accelerating structure; and a pulse compressor which amplifies the high-frequency power supplied to the accelerating structure.
The accelerating structure confines an alternating electric field to the inside thereof. The accelerating structure has an elongated hollow shape formed of a plurality of annular copper discs serially connected on a common axis. Coupler cells are connected to both ends (a most upstream part and a most downstream part) of the accelerating structure, and the coupler cells are coupled to the waveguide outside the accelerating structure.
Patent Literature 1 discloses a technology concerned with an accelerating structure which uses a choke mode cavity.